%I #8 May 12 2023 14:54:33
%S 1,0,-12,360,-7280,-383040,89394624,-8970625664,-316692862720,
%T 470941672802304,-146844936720038912,18279034160407939072,
%U 9932590980055055503360,-8395139128320596309032960
%N sech(arctan(x)*sin(x)) = 1-12/4!*x^4+360/6!*x^6-7280/8!*x^8...
%t With[{nn=30},Take[CoefficientList[Series[Sech[ArcTan[x]Sin[x]],{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Aug 28 2017 *)
%K sign
%O 0,3
%A Patrick Demichel (patrick.demichel(AT)hp.com)